What is an ignition or thermal barrier? 

A thermal barrier is a 15-minute barrier that allows you 15 minutes to get out before the barrier is compromised.

A ignition barrier is a thinner layer of material that helps prevent the foam from igniting, but is not as strong as a thermal barrier. 

A thermal barrier is having spray foam in walls, then the walls get covered with 1/2” of drywall. Or a cathedral ceiling with with foam on the underside of the roof deck with 1/2” drywall attached to the rafter tails.

A thermal barrier IS NOT, having a foamed roof deck on a 2/12 roof pitch with drywall attached to the underside of the ceiling joists. 

In general, what does IRC code want and where?

If the attic is over 30-inches tall and more than 30-square feet, but is only entered for mechanical service, then IRC wants an Ignition Barrier to be installed. 

If the attic has more than a sheet of plywood decking where stuff can be stored, or has a regular walk in door where people could hang out, then IRC wants a Thermal Barrier to be installed. 

What is qualifies as a thermal or ignition barrier?

In 99% of cases, the barrier installed by insulation contractors is called an intumescent coating. This is a “paint” that is sprayed onto the foam AFTER foam is installed.  

What is special about the intumescent coating is that when it comes into contact with a flame, it EXPANDS UP TO 2,000% to thicken and create a barrier between it and the spray polyurethane foam. 

Foam is an uneven surface, so it requires that the coating be sprayed on instead of brushed or rolled on. The viscosity of the coating is such that to install the paint requires about an $8,000 industrial paint sprayer. We use our sprayer almost daily.

Why didn’t Stellrr’s competitors notify me about this building code?

While this is the code requirement, there is a lot of malpractice in the industry. In fact, when my home was built in 2011 by Meritage Homes, I was not in the insulation business yet. My whole house was foamed. My attic required an ignition barrier. I thought my attic had one installed. 

It was not until a few years ago when I had one of my sprayers upgrading my house from R20 to R25 that we realized the original foam company cheated and never got caught. 

The foam company painted my attic foam with interior wall paint. I assumed it was an intumescent coating until my sprayer (who had been installing for 15 years) reminded me that the coating does not come in the color my attic was painted. 

When being built, I had my house inspected by a third party inspector, a city of Austin inspector, and the superintendent. Not one of them caught this scam. 

I suspect there are millions of foamed attics that failed to comply with this code.

Anyway, after upgrading my attic, I also installed not just the Ignition Barrier required, but I upgraded to the Thermal Barrier level just to be safe. 

Do I have to install an intumescent coating? What happens if I decline it?

Stellrr’s job is to inform you of what is supposed to be done. If you knowingly decline the protection, that is your choice. 

I have never heard of a Fire Marshall going an inspecting an individuals attic when they have a drywall ceiling. 

(In Round Rock we foamed Fire Station #1, and got to install a Thermal Barrier to the entire roof, including in the Fire Marshall’s office. That was fun!)

However, here is what I have seen happen. If you house gets struck by lightning, or has an electrical fire… and you don’t have a code compliant intumescent coating… how much risk can you tolerate? Will your insurance company approve or deny your claim because they have your foam tested and find out that you don’t have an intumescent coating? What happens when you go to sell the house, will you have to pay for it then?

What are the alternatives to an intumescent coating?

Foam manufacturers know that this code is an added cost. So they have attempted other types of lab tests. One of which is called a Corner Burn Test. Where they start a fire in a corner, and use Oxygen Deprivation to extinguish or manage the fire. While this fire testing can be effective, it is not code approved. 

With that said, I have been documenting sealed, spray foamed attic fire occurrences across North America. I talk to other foam companies monthly about these cases, whether or not there was an intumescent coating, and look at the photos.  What I have found is that properly installed foam, does seem to suffocate the fire. The homes are much more intact than homes with a leaky fiberglass building envelope that feeds the fire, allowing fire to spread. I don’t see melted foam, if anything it has smoke damage or a little char. 

There are also homes like one sprayed by a competitor in Liberty Hill that was 1 year old and had a dryer vent fire. We did the demolition on the house with my sister company Dumposaurus. The entire house had to be demolished. 

What about Appendix X foam that has some ignition barrier in it? Is that good enough?

We used to install Appendix X (OCX) foam, but will never again. OCX is a weak attempt at an ignition barrier and very fickle. First, it still does not meet code, regardless of what you may be told. Second, the B side (resin) is sugar based. Aren’t we supposed to try to repel insects and rodents instead of attract them!? Third, it is prone to a number of installation errors that installers can cover up but leave you with a damaged home. The OCX has to be constantly agitated in the 55 gallon drum. and the installer cannot take any breaks or the resin separates in the hose, and is bad. If the foam gun is idle for 10+ minutes, everything has to be broken down, flushed out, and re-started. Do you think the installers like all this extra work or do they take shortcuts?

So what happens is when these installers start spraying bad foam, they just spray it and try to cover it up with the good stuff later. If you ever pull back a handful of foam in your attic and see Swiss cheese or honeycomb, you have bad OCX hidden in your attic. This is common. Very hard to manage, and is just one more reason why we will not install this formula. 

What if I wait to have the ignition barrier installed later?

Some people go this route. Installing it is has to happen after the foam is installed. So we can wait a few days, weeks, or longer to install it. But, the question is, how much risk are you comfortable taking on. Your decision. 

Building Code Specifics for Ignition Barriers

International Residential Code (IRC) Requirements:

  1. Attic access required: ≥ 30” high1 and ≥ 30ft2
  2. The space is entered only for the purposes of repairs or maintenance.

Ignition Barrier Options:

Prescriptive: (R316.5.3) 1 1/2-inch-thick mineral fiber insulation; 1/4-inch-wood structural panels (OSB or plywood); Corrosion resistant steel 0.016 inch; 3/8-inch gypsum board; etc. 3/8-inch particleboard; 1/4-inch hardboard.

Performance: Same as Thermal Barrier but the testing requirement is reduced to the first five minutes of the testing protocol.

Building Code Specifics for Thermal Barriers

International Residential Code (IRC) Requirements:

  1. Attic access required: ≥ 30” high1 and ≥ 30ft2
  2. The space is intended for attic storage.

Thermal Barrier Options:
Prescriptive: 1/2” gypsum wallboard
Performance: An assembly tested in accordance with NFPA 286 and ICC-ES AC377 with the acceptance criteria of (required full 15-minute burn). This is a performance test that evaluates the foam and possibly other products in their end-use configuration. Passing of this test depends on the chemistry of the foam and in many cases protective coatings over the foam. Tests should be conducted by third-party certified laboratories.

If Stellrr is not hired to install an intumescent thermal barrier coating, your Fire Marshall will require 1/2 gypsum (or other approved thermal barrier) to be installed over sprayed polyurethane foam insulation.

Spray machine requirements: minimum of a 3300psi and 1.3gpm machine, this is not something you can rent. These sprayers start at $9,000.